350-401 Virtual Machines and Hypervisors Practice Question
This 350-401 practice question tests your understanding of virtual machines and hypervisors. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A network engineer is migrating a physical server running a critical database to a virtual machine on a VMware vSphere cluster. The database requires high I/O performance and low latency. The engineer decides to use VMFS datastores with multiple extents to improve performance. After migration, the database performance is worse than on the physical server. What is the most likely reason?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
VMFS datastores with multiple extents can cause I/O to span multiple LUNs, increasing latency.
VMFS datastores with multiple extents distribute data across multiple LUNs, which can cause I/O operations to span physical storage devices. This introduces additional latency due to the need for coordination across LUNs, negating the performance benefit expected from a single, contiguous LUN. For a database requiring high I/O and low latency, this spanning effect degrades performance compared to a physical server with direct-attached storage.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
VMFS datastores with multiple extents can cause I/O to span multiple LUNs, increasing latency.
Why this is correct
Correct because multiple extents can lead to I/O being split across LUNs, adding overhead.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The VMFS datastore does not support files larger than 2 TB.
Why it's wrong here
Incorrect because VMFS supports large files with extents.
✗
The virtual disk is configured as thin provisioned, causing write amplification.
Why it's wrong here
Incorrect because thin provisioning can affect performance but is not directly related to extents.
✗
The virtual disk is configured as thick eager zeroed, causing slow initial writes.
Why it's wrong here
Incorrect because thick eager zeroed disks have good performance after initialization.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that multiple extents improve performance by aggregating bandwidth, when in fact they increase latency due to I/O spanning and SCSI locking overhead.
Detailed technical explanation
How to think about this question
VMFS extents allow a datastore to span multiple LUNs, but I/O to a virtual disk may be striped across these LUNs, increasing latency due to SCSI reservation conflicts and path switching. In vSphere, using a single LUN per datastore avoids this, and for databases, VMFS-5 with a single extent or vSAN is recommended to maintain low latency. Real-world scenarios show that multi-extent datastores are often used for capacity, not performance, and can cause unpredictable I/O behavior under load.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 350-401 question in full detail.
Virtual Machines and Hypervisors — This question tests Virtual Machines and Hypervisors — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: VMFS datastores with multiple extents can cause I/O to span multiple LUNs, increasing latency. — VMFS datastores with multiple extents distribute data across multiple LUNs, which can cause I/O operations to span physical storage devices. This introduces additional latency due to the need for coordination across LUNs, negating the performance benefit expected from a single, contiguous LUN. For a database requiring high I/O and low latency, this spanning effect degrades performance compared to a physical server with direct-attached storage.
What should I do if I get this 350-401 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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